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A. HAARMANN MINE POST Filed April 17, 1951 Fig. 1

May 29, 1956 Fig. 4

Inventor ARA/OLD HAARAUM/N AlfbR/VEY United. States Patent MINE POST Arnold Haarmann, Brambauer, Westphalia, Germany, assignor to Becorit-Grubenausbau G. m. b. H., Reeklinghausen, Germany, a German firm Application April 17, 1951, Serial No. 221,353

Claims priority, application Germany April 18, 1950 1 Claim. (Cl. 248354) The invention relates to mine posts having a pedestal or base member, an inner movable member or column mounted upon said base member and adapted to move longitudinally thereof and means for rigididly locking the said inner base member or column in working position and for longitudinally adjusting its position on the pedestal.

The inventor has experienced that in the known mine posts the clamping jaw or the friction plate provided therein is subjected to a higher wear in its upper portion than in its lower portion; this may be explained by the fact that the moving inner member displaces the clamping jaw for a very small and practically not measurable angle, thereby increasing the surface pressure in the upper region of the clamping jaw and diminishing said pressure in the lower region. A further disadvantage arises insofar as the inner or movable member of the mine post is subjected in the upper portion of the clamping jaw to essentially higher surface pressures than calculated, whereby disadvantageous deformations of the mine post profile may result.

It is one characteristic feature of the invention to avoid these drawbacks. According to the invention care is taken not to arrange the supporting surface engaged by the rocking member in the horizontal middle plane of the clamping jaw as is customary up to now, but to displace it relatively to the middle plane in the moving direction of the inner and movable member; said surface lies generally below the said horizontal middle plane. The amount of the displacement depends on the proportion of the height of the clamping jaw to the thickness of the rocking member. In the usual construction of the mine posts where the height of the clamping jaw is a multiple of the thickness of the rocking member, the most favourable results are attained, it, according to the invention, the horizontal middle line of the said supporting surface is displaced relatively to the horizontal middle line of the clamping jaw for about one sixth of the height of the jaw.

The invention is of particular importance in connection with mine posts of the here described kind, in which the inner or movable member drives the clamping jaw for a small amount, as soon as said member commences to move down. However, the invention may also be successfully used, if the clamping jaw is not driven by the said movable member or if the clamping jaw is mechanically brought into its end position after the mine post has been set, whereby the requested transversal tension is already produced before the roof pressure acts upon the post. The invention may further be used in connection with clamping jaws provided with a friction plate consisting of an aluminum alloy or in connection with clamping jaws consisting themselves of a material having a high coefficient of friction. The idea of the invention is, however, of special practical importance in connection with embodiments, in which bead-like ribs of hard metal or the like are welded on the movable 2,747,828 Patented May 29, 1956 member, as such movable member will increase the tendency of the clamping jaw to rock.

The drawing shows by way of example an embodiment of the invention.

Fig. l is a view of a clamping jaw according to the invention;

Fig. 2 illustrates the proceedings arising with the new improved clamping jaw;

Fig. 3 is a vertical section through Fig. 4 according to the line BB of the mentioned figure and shows a mine post according to the invention;

Fig. 4 is a section through Fig. 3 according to the line A-A.

The mine post described in Figs. 3 and 4 comprises a movable member 1, of which the longitudinal cross section is rectangular or has a slight wedge-like inclination. In the lock 3, fastened on the base member 2, a clamping jaw 4 is provided, the one side-face of which engages the movable member. At the rear side of the clamping jaw 4 a recess 5 is provided which is adapted to receive a rocking wedge 6. The opposite side of this rocking wedge is supported by an abutment 7 of the clamp 3. To the movable member 1 rounded ribs 8 of hard metal are applied.

Fig. 1 shows the clamping jaw shown in Figs 3 and 4 on a greater scale. It may be seen that the horizontal median line of the pan 5 is displaced relatively to the horizontal median line x-x of the clamping jaw in the moving direction of the movable members for an amount y. This amount preferably corresponds to about one sixth of the height of the jaw.

As shown in Fig. 2 the clamping jaw 4 is to rock in the sense of the arrow z, if the column or movable mem ber move downwardly and the jaw is pressed against said column by the rocking wedge 6. In consequence of the mentioned displacement of the supporting surface 5 a nearly uniform surface pressure is attained over the entire height of the clamping jaw 4 if the mine post is loaded.

Having thus particularly described the nature of my said invention and the manner in which the same is to be performed what I wish to have covered by Letters Patent is:

A mine prop comprising an outer tubular base member and an inner tubular upper member adapted to ver tically slide in said base member, a locking member for said two prop members and supported upon the upper end of said base member, a locking jaw supported by said locking member, said locking jaw contacting the outer face of said slidable upper prop member and having an approximately half circular recess located at a distance equalling one sixth of the entire length of said locking jaw underneath its median line, an abutment jaw located in said locking member and having an approximately half circular recess corresponding in shape to the recess of said locking jaw and a wedge shaped locking arm located with its opposite sides in the recess of said locking jaw and of said abutment.

References Cited in the file of this patent UNITED STATES PATENTS 2,445,543 Thines July 20, 1948 2,450,374 Gillett Sept. 28, 1948 FOREIGN PATENTS 889,430 France Jan. 10, 1944 273,983 Great Britain July 14, 1927 633,989 Great Britain Dec. 30, 1949 

